Excess Lead in the Neural Retina in Age-Related Macular Degeneration

Purpose

To measure lead and cadmium in retinal tissues of human donor eyes with and without age-related macular degeneration (AMD).

Design

Laboratory investigation.

Methods

Lead and cadmium concentrations in retinal tissues (neural retina and retinal pigment epithelium [RPE]–choroid complex) in 25 subjects with AMD (50 donor eyes) and 36 normal subjects (72 donor eyes) were determined by using inductively coupled plasma-mass spectrometry. Severity of AMD was graded by using color fundus photographs and the Minnesota Grading System. Differences in metal concentrations were compared by using Wilcoxon rank-sum tests.

Results

The neural retinas of subjects with AMD had increased lead concentrations (median, 12.0 ng/g; 25% to 75% interquartile range, 8 to 18 ng/g; n = 25) compared with normal subjects (median, 8.0 ng/g; 25% to 75% interquartile range, 0 to 11 ng/g; P = .04; n = 36). There was no difference in lead concentration in the RPE–choroid complex between subjects with AMD (median, 198 ng/g; 25% to 75% interquartile range, 87 to 381 ng/g) and normal subjects (median, 172 ng/g; 25% to 75% interquartile range, 100 to 288 ng/g; P = .25). Cadmium concentration in the neural retina (median, 0.9 μg/g; 25% to 75% interquartile range, 0.7 to 1.8 μg/g) and RPE–choroid complex (median, 2.2 μg/g; 25% to 75% interquartile range, 1.8 to 3.7 μg/g) in subjects with AMD was not different from concentrations in the neural retina (median, 0.9 μg/g; 25% to 75% interquartile range, 0.7 to 1.4 μg/g; P = .32) and RPE–choroid complex (median, 1.5 μg/g; 25% to 75% interquartile range, 0.9 to 2.5 μg/g; P = .12) of normal subjects.

Conclusions

AMD is associated with excess lead in the neural retina, and this relationship suggests that metal homeostasis in AMD eyes is different from normal.